W型潜坝作为一种新型的堰坝结构,不仅具有消能、护岸、分流和改善通航条件等功能,而且具有显著的生态功能。选取鲫鱼幼鱼为目标鱼类,研究不同粒径组成的W型潜坝的河流流速分布及对目标鱼类聚集的影响,探明W型潜坝的生境改良效果,为裁弯...W型潜坝作为一种新型的堰坝结构,不仅具有消能、护岸、分流和改善通航条件等功能,而且具有显著的生态功能。选取鲫鱼幼鱼为目标鱼类,研究不同粒径组成的W型潜坝的河流流速分布及对目标鱼类聚集的影响,探明W型潜坝的生境改良效果,为裁弯河段生态涵养区建设提供依据。研究结果表明不同粒径的W型潜坝作用下,[10,20]mm较大粒径组成的W型潜坝透水性更好,流速梯度小于小粒径组,流态多样性高。在流量0.09 m 3/s条件下,[10,20]mm粒径组成的W型潜坝鱼类聚集区域停留最多达到85次;[10,20]mm较大粒径组成的W型潜坝生境多样性高,可以为试验鱼提供更好的栖息和庇护场所。因此,在人工运河修建中裁弯河段生态涵养区建议选透水效果较好的大粒径潜坝方案。流态多样性指数与鱼类平均聚集度存在线性关系,可作为评价栖息地质量的依据,研究成果为河流生境异质性研究和生态优化设计提供理论支撑。展开更多
[Background]Traveling-wave tubes(TWTs)are widely applied in radar,imaging,and military systems owing to their excellent amplification characteristics.Miniaturization and integration are critical to the future of TWTs,...[Background]Traveling-wave tubes(TWTs)are widely applied in radar,imaging,and military systems owing to their excellent amplification characteristics.Miniaturization and integration are critical to the future of TWTs,with multi-channel slow-wave structures(SWSs)forming the foundation for their realization in high-power vacuum electronic devices.[Purpose]To provide design insights for multi-channel TWTs and simultaneously enhance their output power,a W-band folded-waveguide TWT with dual electron beams and H-plane power combining was proposed.[Methods]Three-dimensional electromagnetic simulations in CST were conducted to verify the highfrequency characteristics,electric field distribution,and amplification performance of the proposed SWS,thereby confirming the validity of the design.[Results]Results indicate that the designed TWT achieves a transmission bandwidth of 10 GHz.With an electron beam voltage of 17.9 kV and a current of 0.35 A,the output power reaches 450 W at 94 GHz,corresponding to an efficiency of 7.18%and a gain of 23.5 dB.Moreover,under fixed beam voltage and current,the TWT delivers over 200 W output power across 91–99 GHz,with a 3 dB bandwidth of 91–98.5 GHz.The particle voltage distribution after modulation further validates the mode analysis.[Conclusions]These results demonstrate the feasibility of compact dual-beam power-combining structures and provide useful guidance for the design of future multi-channel TWTs.展开更多
文摘W型潜坝作为一种新型的堰坝结构,不仅具有消能、护岸、分流和改善通航条件等功能,而且具有显著的生态功能。选取鲫鱼幼鱼为目标鱼类,研究不同粒径组成的W型潜坝的河流流速分布及对目标鱼类聚集的影响,探明W型潜坝的生境改良效果,为裁弯河段生态涵养区建设提供依据。研究结果表明不同粒径的W型潜坝作用下,[10,20]mm较大粒径组成的W型潜坝透水性更好,流速梯度小于小粒径组,流态多样性高。在流量0.09 m 3/s条件下,[10,20]mm粒径组成的W型潜坝鱼类聚集区域停留最多达到85次;[10,20]mm较大粒径组成的W型潜坝生境多样性高,可以为试验鱼提供更好的栖息和庇护场所。因此,在人工运河修建中裁弯河段生态涵养区建议选透水效果较好的大粒径潜坝方案。流态多样性指数与鱼类平均聚集度存在线性关系,可作为评价栖息地质量的依据,研究成果为河流生境异质性研究和生态优化设计提供理论支撑。
基金National Key Research and Development Program of China(2022YFF0707602)National Natural Science Foundation of China(62471097,62471115,62471101)National Natural Science Foundation of Sichuan(2025ZNSFSC0537)。
文摘[Background]Traveling-wave tubes(TWTs)are widely applied in radar,imaging,and military systems owing to their excellent amplification characteristics.Miniaturization and integration are critical to the future of TWTs,with multi-channel slow-wave structures(SWSs)forming the foundation for their realization in high-power vacuum electronic devices.[Purpose]To provide design insights for multi-channel TWTs and simultaneously enhance their output power,a W-band folded-waveguide TWT with dual electron beams and H-plane power combining was proposed.[Methods]Three-dimensional electromagnetic simulations in CST were conducted to verify the highfrequency characteristics,electric field distribution,and amplification performance of the proposed SWS,thereby confirming the validity of the design.[Results]Results indicate that the designed TWT achieves a transmission bandwidth of 10 GHz.With an electron beam voltage of 17.9 kV and a current of 0.35 A,the output power reaches 450 W at 94 GHz,corresponding to an efficiency of 7.18%and a gain of 23.5 dB.Moreover,under fixed beam voltage and current,the TWT delivers over 200 W output power across 91–99 GHz,with a 3 dB bandwidth of 91–98.5 GHz.The particle voltage distribution after modulation further validates the mode analysis.[Conclusions]These results demonstrate the feasibility of compact dual-beam power-combining structures and provide useful guidance for the design of future multi-channel TWTs.
